Kandidatuppsats
Biomedicin - inriktning fysisk träning 180 hp
Standing long jump compared to vertical
jump as a field test for assessing leg power in firefighter trainees
A correlation study from a gender equality perspective
Examensarbete inom träningens biomedicin 15 hp
Halmstad 2021-06-07
Standing long jump compared to vertical jump as a field test for assessing leg power in firefighter trainees: a correlation study from a
gender equality perspective
Mimmi Bringsén-Bornegrim
21-06-07
Bachelor Thesis 15 credits in Exercise Biomedicine Halmstad University
School of Business, Innovation and Sustainability
Acknowledgments
The author would like to thank supervisor Emma Haglund, who has been very helpful and most of all patient. A big thank you also to Halmstad Rescue Service who in many ways been a great support during the work with the study. A special thank you to teacher Ulf Ekberg, at the rescue school in Revinge, who contributed to this study with great commitment and help- fulness. Finally, a big thank you to all subjects, without whom the study would not have been possible.
Abstract
Background: Within the rescue service, a varied background is needed to increase the possi- bility of delivering equal service to the citizens. At present, there is a skewed gender distribu- tion within the municipal rescue services, with only a couple of percent of the firefighters be- ing women. Many women find it difficult to meet the physical limit values on recruitment tests. The standing long jump (SLJ) is used as a part of recruitment tests on many rescue ser- vices, to assess leg power. It is not clear though whether SLJ is the most appropriate field-test to assess leg power in firefighter trainees, with men and women mixed in the same group, as it has been argued that anthropometric factors, such as body height (BH), affects the result.
Thereby we wanted to study the relationship between BH and SLJ, and compere SLJ with an- other field-test for measuring leg power, one that omits the variable BH. Aim: The aim was to study the strength of the relationship between body height and the jump length at standing long jump, for firefighter trainees. A second aim was to study the strength of the relationship between firefighter trainees' jump results of the two tests: standing long jump and vertical jump. Methods: The study was executed as an observational cross-sectional study. Three dif- ferent measurements were carried out: BH, vertical jump (VJ) and SLJ. Correlation analyzes, with Pearson's correlation coefficient, were performed on BH in relation to SLJ, and VJ in re- lation to SLJ. Results: Fourteen (n = 14) firefighter trainees (women n = 5, men n = 9) met the inclusion criteria and participated in the study. Subjects' age, body mass index (BMI) and number of workouts per week were 29 ± 7 years old, 25 ± 2 kg/m2 and 4 ± 1 workouts (at least 30 minutes) per week. Results showed a significant moderate correlation between BH and SLJ (r = 0.572). Between the variables VJ and SLJ there were a significant strong correla- tion (r = 0.862). However, the results changed substantially when the analyzes were per- formed separately for men and women, with a very low correlation level (r = 0.106 respective r = 0.166) between BH and SLJ. For VJ and SLJ there were a moderate correlation level for men and low for women (r = 0.414 respective r = 0.387). Conclusion: The result from this study is in line with aforementioned work and supports the hypothesis that BH to some extent can affect the jump result at SLJ. Our study complements earlier work and indicates that these results are also applicable to firefighter trainees. The findings in this study indicates VJ could possibly be an alternative field test for SLJ, to assess leg power when recruiting new firefight- ers. Additional studies are required to investigate the correlation between SLJ and VJ with ad-
Table of contents
1. Background ... 1
1.1 Gender distribution ... 1
1.2 Physical demands ... 2
1.3 Maximum muscular power ... 3
1.4 Testing maximum muscular power ... 4
1.5 Aim ... 6
1.5.1 Research questions ... 6
2. Methods ... 6
2.1 Subjects ... 6
2.2 Preparations ... 7
2.3 Procedure ... 7
2.4 Statistical analyzes ... 9
2.5 Ethical considerations ... 9
2.6 Social considerations ... 10
3. Results ... 10
3.1 Correlation between body height and jump length ... 11
3.2 Correlation between jump height and jump length ... 13
4. Discussion ... 15
4.1 Result discussion ... 15
4.2 Method discussion ... 17
5. Conclusion ... 18
References ... 19
Appendices ... 23
Informed consent ... 23
Questionnaire ... 26
1. Background
Within the rescue service, a varied background and different skills are needed to increase the possibility of delivering equal service to the citizens (Lindberg & Malm, 2011; The Swedish Civil Contingencies Agency (MSB), 2018). At present, there is a skewed gender distribution within the municipal rescue services, with only a couple of percent of the firefighters being women (MSB, 2018). Many women find it difficult to meet the physical limit values on re- cruitment tests (Lindberg et al., 2011; MSB, 2018). The standing long jump (SLJ) is used as a part of recruitment tests on many rescue services, as a field test to assess leg power (Lindberg et al., 2011). However, it has been argued that SLJ is very technical, and biomechanical as well as anthropometric factors such as body height (BH) and weight affect the result. Based on this, we hypothesized that men applying for the firefighter profession may have an ad- vantage over women, in this part of the recruitment process. This because men generally are taller than women (Statistics Sweden, 2017). SLJ has shown a moderate to strong correlation (r = 0.61 - 0.911) to the vertical jump (VJ) (Castro-Pinero et al., 2010; Markovic et al., 2004).
At the VJ, the variable body height is omitted, hence a second hypothesis was that the VJ would possibly be a more equal test to assess leg power when recruiting new firefighters.
Gender equality is an important issue that is also addressed in United Nations (n.d.) Sustaina- ble Development Goals. To achieve equality between women and men as colleagues in the firefighter profession, it is important to regularly evaluate recruitment tests to ensure that they are valid and reliable, as well as the most equal tests, in modern times. No one should be ex- cluded from a profession on unreasonable grounds (Lindberg, Oksa, Antti & Malm, 2015;
SFS 2008:567), and an overly homogeneous workforce affects the ability to provide equal service to the citizens (MSB, 2018).
1.1 Gender distribution
Skydd Mot Olyckor (SMO) is a college in the fields of fire safety, emergency services, crisis management, medicine and behavioral science. In year 2018, the gender distribution in the SMO education was 83% men and 17% women (MSB, 2018). However, only half of the women who have completed this education later works in the rescue service. A survey MSB had done in 2012 (cited in MSB, 2018) indicated that many women by then did not pass the
(Grundutbildning för räddningstjänstpersonal i beredskap). The students in this education al- ready have an employment in the municipal rescue service as a part-time firefighter. In 2017, the proportion of women among part-time firefighters was 6.5%. During the same year, the number of full-time female firefighters were 5.1% (MSB, 2018). Gender equality have been a recurring assignment in the authority's (first the Swedish Rescue Services Agency which later became MSB) letter of regulation since 1997. However, the number of women within the mu- nicipal rescue services is still very low, which is why more work is needed.
1.2 Physical demands
Fireman's professional role is complex, and physical ability is only part of the work require- ments (Lindberg et al., 2011; Malm, Lindberg & Stene, 2005; MSB, 2018). However, some work tasks can mean great demands on the physical ability (Bos, Mol, Visser & Freds-
Dresen, 2004; Gavhed, Brodin, Johansson, Bohlund, Thoresson, Åslund & Lundström, 2001;
Peterson, Dod, Alvar, Rhea & Favre, 2008). The heaviest among the most common work tasks a Swedish firefighter must handle are: cutting a hole in the roof (vertical ventilation), vehicle extrication (removing a vehicle from around a person), carry hose baskets in terrain, carry hose baskets in stairwell, pulling hose, tearing down a ceiling, and drag out victims (Gavhed et al., 2001). Malm et al. (2005) have found a correlation between the above mentio- ned work tasks and the following physical tests: maximal grip strength, rowing 500 meters, bench press, SLJ, chin lift, and running 3000 meters. When the rescue services recruit new firefighters, physical tests are often performed, but each municipality decides for itself if and which tests are to be included in the recruitment process (Gavhed et al., 2001). Further studies have determined limit values for the physical work capacity for above mentioned tests (Table 1), where the results are directly related to work performance (Lindberg et al., 2011). The study by Lindberg et al. (2011) states that more men than women pass the physical limit val- ues, due to a generally higher quantity of muscle. On all tests, however, there was always at least one woman who performed better than the worst man. This in line with the study by Bishop et al. (1987) showing a significative difference between men and women in terms of absolute strength. When comparing strength relative to muscle cross-sectional area, there were almost no differences in strength between the sexes. Women, however, are generally shorter than men (Statistics Sweden, 2017). Lindberg (2011) found that BH affects the results of several of the firefighters' heaviest among the most common tasks. Meanwhile Williams- Bell et al. (2009) who examined the performance on a work-related course
(Candidate Physical Ability Test) with stages relevant to the firefighter profession in the USA, could not find any statistical difference in BH between those who completed and did not complete the course. Lindberg, Oksa, Antti & Malm (2015) also establish that their mod- els excluding anthropometric data were valid for prediction of physical work capacity for fire- fighting work tasks. According to Swedish law (SFS 2008:567) it is not allowed to apply a procedure, even if it appears neutral, but which may be particularly disadvantaged for a parti- cular sex. This unless the procedure has a legitimate purpose and resources used are appropri- ate and necessary to achieve the purpose. More studies that further examine the physical re- quirements for firefighters and evaluate the physical tests in the recruitment process, and this in relation to sex differences, are therefore important for the profession.
Table 1. Physical limit values in recruitment tests for firefighters.
Test score Standing long jump (cm)
Bench press 30 kg (num- ber)
Rowing 500
m (sec) Running 3000 m (sec / kg body weight)
Upright row 15 kg (num- ber)
Maximal grip strength (kg)
1 180 20 130 14.5 20 30
2 186 22 126 14,0 22 32
3 192 24 122 13.5 24 34
4 198 26 118 13.0 26 36
5 204 28 114 12.5 28 38
6 210 30 110 12.0 30 40
7 218 32 106 11.5 32 42
8 226 34 102 11.0 34 44
9 234 36 98 10.5 36 46
10 242 38 94 10.0 38 48
11 250 40 90 9.5 40 50
Table presents physical limit values in recruitment tests for firefighters, suggested by Lindeberg et al. (2011).
1.3 Maximum muscular power
Maximum muscular power has shown to be an important factor of firefighters’ rescue, pulling and stairs work capacity (Lindberg et al., 2015). The definition of power in this context is the
Ratamess, Alvar, Evetoch, House, Kibler, Kraemer & Triplett, 2009). Both strength (the abil- ity to produce force) and speed are physical abilities that can be trained. Strength is depended upon several biomechanical factors, including neural control, muscle cross-sectional area, muscle fiber arrangement, muscle length, joint angle, muscle contraction velocity, joint angu- lar velocity, body weight and body height (Baechle & Earle, 2008, p. 75 - 79). Neural control being mentioned as the most important factor for maximum muscular power as it affects the maximal rate of force development (RFD), force production at slow and fast contraction ve- locities, stretch-shortening cycle performance, and coordination of movement pattern and skill (Ratamess et al., 2009). Maximum power efforts for about 1 to 2 seconds, as SLJ, require a rapid energy release. The primary energy source for this type of work is adenosine triphos- phate (ATP) stored in the active muscles (Baechle et al., 2008; Chamari & Padulo, 2015;
Manske, 2013). To ensure full recovery after such work efforts, rest periods of at least 2 - 3 min between sets are recommended (Ratamess et al., 2009). Firefighters’ rescue, pulling and stairs work are parts of a larger tasks a firefighter must handle (Gavhed et al., 2001). Lindberg et al. (2015) propose testing leg power, in combination with other physical tests, when recruit- ing new firefighters. At the time of conducting this study, we did not know of any studies that compared different power tests for firefighter trainees.
1.4 Testing maximum muscular power
SLJ is used as a part of recruitment tests on many rescue services, to assess leg power (Lind- berg et al., 2011). In the study by Lindberg et al. (2011), studying recruitment tests for fire- fighters, many women have difficulty performing the 180 cm at SLJ, which is the recom- mended lower limit when recruiting new firefighters (Table 1). After bench press, SLJ is the second test that most women fail in. This compared to the men in the study where almost eve- ryone manages the lower limit, and about half of them reach the upper limit at 250 cm. It is not clear though whether SLJ is the most appropriate field-test to assess leg power in fire- fighter trainees, with men and women mixed in the same group, and this has received media attention (Hilmersson, 2020, December 21; Ivansson, 2012, May 25). More studies are needed that compare different tests for leg power on the study population firefighter trainees, which considers biological sex differences such as BH. Other field tests for measuring leg power are: squat jump (SJ), countermovement jump (CMJ), and VJ (Castro-Pinero et al., 2010; Markovic et al., 2004), all of them omits the variable BH. CMJ has shown the greatest
(r = 0.87) validity of all mentioned tests (Markovic et al., 2004). However, VJ has been re- ported with the strongest correlation to SLJ (r = 0.61 - 0.911), compared to the other two tests mentioned, why VJ was chosen as the comparable test in this study (Castro-Pinero et al., 2010; Markovic et al., 2004).
1.4.1 Standing long jump
At SLJ the subject performs a countermovement and jump as far as possible horizontally (Castro-Pinero et al., 2010; Lindberg et al., 2011). It has been argued that SLJ has questiona- ble validity because it is very technical, and biomechanical as well as anthropometric factors, such as BH and weight, affects the result (Castro-Pinero et al., 2010). In the study by Ashby and Heegard (2002), performed on three adult men, they found arm swing contributed with 21.2 % of the jump distance in SLJ. Other researchers state that jumping with 90° knee initial angle with free arm motion results in a longer (p < 0.05) jump compered to variations with 45° knee flexion jumping and restricted arm motion (Wu, Wu, Lin, and Wang 2003). This shows the importance of technical skills and good coordination to be able to perform on the test. Several studies have shown that underweight and normal weight (based on their BMI, calculated as weight divided by BH squared (kg / m2)) children and adolescents had signifi- cantly (p < 0.05) better scores compered to overweight and obese subjects (Castro-Pinero et al., 2009; Milliken, Faigenbaum, Loud and Westcott, 2008). A study on young women, how- ever, found only low correlation levels between jump length and BH (r = 0.18 - 0.29) (Wu, Wu, Lin, & Wang, 2003). However, it is shown that BH to some extent affects jump perfor- mance at SLJ (Castro-Pinero et al., 2009; Milliken, et al., 2008; Wu et al., 2003). Further studies are required to investigate if these results are also applicable to firefighter trainees.
1.4.2 Vertical jump
VJ does not require any advanced equipment but can be done with a piece of chalk and a wall.
SLJ and VJ are quite similar filed tests for measuring leg power. In VJ, however, it is the jump height that is measured. BH is subtracted from the jump result which is why it cannot affect the result in the same way as in SLJ. VJ, like SLJ, depends much on technical skills as well as biomechanical factors and body weight (Castro-Pinero et al., 2010). Arm swing con- tributes with 8 –14 % of the jump height (Castro-Pinero et al., 2010).
1.5 Aim
The aim was to study the strength of the relationship between body height and the jump length at standing long jump, for firefighter trainees. A second aim was to study the strength of the relationship between firefighter trainees' jump results of the two tests: standing long jump and vertical jump.
1.5.1 Research questions
The research questions in the study were: (1) how strong is the correlation between body height and the standing long jump, for firefighter trainees? (2) how much of the variation in jump length can be explained by body height, for firefighter trainees? (3) how strong is the correlation between the vertical jump and the standing long jump, for firefighter trainees?
2. Methods
The study was executed as an observational cross-sectional study. Due to the current Covid- 19 pandemic data was collected during several test occasions, one for each subject. To attain a sufficient number of subjects, despite the time-consuming set-up, the outcome was two differ- ent places with two different types of floor surfaces. Seven subjects were tested in a gym with wooden sports floor, and seven subjects were tested in a room with concrete floor. In excess of that, all sessions were performed under the same environmental conditions, although on different times of the day. Four subjects were tested in the morning and ten subjects were tested in the afternoon.
2.1 Subjects
Subjects were recruited through advertisements on student portals, and mailings including the informed consent (Appendix 1). The inclusion criteria were, students from any of the fire- fighter courses SMO or GRIB, men and women, in the age group 20-45 years. Those who chose to participate in the study answered a questionnaire (Appendix 2) containing questions about school affiliation, weight, sex, number of workouts per week, type of training, and pos- sible health problems. Persons who trained at an elite level or regularly performed specific power exercises, were excluded from the study (n = 3). Definition of elite level were a subjec- tive assessment of the subject himself/herself. Regularly were defined as: at least twice a week, during the last six months. Subjects who in matters of their health were deemed unfit to
perform hard physical work (i.e., illness or unhealed injuries) were also excluded from the study (n = 1).
2.2 Preparations
In order to maximize the reliability of the tests, those who chose to participate in the study were asked to rest from training the day before the test session and to avoid heavy training two days before. The subjects were also advised not to eat a large meal less than two hours before the tests (Appendix 1; Baechle et al., 2008).
2.3 Procedure
At the test session, subjects wore training clothes and shoes. The subjects were once again in- formed about the study, and were able to ask questions, thereafter the signed informed con- sents (Appendix 1) were collected. Testing procedure began with a standardized warm-up, followed by 10 minutes of recovery before the test jumps were performed (Tsurubami, Oba, Samukawa, Takizawa, Chiba, Yamanaka, & Tohyam, 2020). During recovery, measurement of BH and preparations for VJ was done. Thereafter the jump-tests were carried out, firstly VJ and then SLJ (Manske et al., 2013). All subjects performed the tests in the same, mentioned order. Both VJ and SLJ followed the same format regarding number of attempts and resting time between each test. The subjects had two attempts on each test, only the best attempt was used in the analysis (Castro-Pinero et al., 2010). Between test jumps there was 2-3 minutes of recovery (Manske et al., 2013; Ratamess et al., 2009).
2.3.1 Warm-up
The standardized warm-up (Appendix 3) was based on a warm-up protocol for enhanced jump performance, as described in the study by Pagaduan, Pojskić, Užičanin and Babajić (2012). Our aim with the warm-up was to prepare the subjects both mentally and physically for the test demands, and reduce the risk of injury (Manske et al., 2013). Warm-up involved five minutes of jogging and ten minutes of specific warm-up with dynamic stretching and dif- ferent types of jumps. Subjects were asked to keep a moderate to high intensity during warm- up, to further maximize the jump performance (Tsurubami et al., 2020). During the warm-up the subjects also got trials at VJ and SLJ to reduce the risk that test results would improve due
to a learning effect (Manske et al., 2013). The warm-up was led by an instructor to ensure uni- formity (Baechle et al., 2008).
2.3.2 Body height
Height was measured without shoes and rounded to the nearest 0.5 cm (Baechle et al., 2008) using a stadiometer (Seca 217, Seca, Hamburg, Germany).
2.3.3 Vertical jump
The vertical jump has previously been shown to have a good test-retest reliability between 0.93-0.99 (Manske et al., 2013), and high validity (r = 0.80) (Markovic et al., 2004). Execu- tion of the test followed previous protocols (Baechle et al., 2008, p. 256; Castro-Pinero et al., 2010; Manske et al., 2013). The subject stood with the dominant side at a mark about 15 cm from a wall. With a single arm and chalk on the fingers, the subject extended and marked as high as possible on the wall. Thereafter the subject jumped as high as possible and marked with chalk on the wall at the highest point. Arm movements were encouraged. The score was the distance between the first reach and the highest mark after two jump attempts. The result was rounded to the nearest centimeter.
2.3.4 Standing long jump
The standing long jump has previously been shown to have a good test-retest reliability be- tween 0.83-0.99 (Castro-Pinero et al., 2010; Manske et al., 2013). Validity have been reported to be high (r = 0.76) when estimating maximal power (Markovic, Dizdar, Jukic & Cardinale, 2004). Execution of the test followed previous protocols (Castro-Pinero et al., 2010; Lindberg et al., 2011). The subjects were instructed to start the jump standing with feet hip-wide and the toes behind a piece of tape on the floor. They were then instructed to jump as far as possi- ble horizontally. Arm movements were encouraged. The subjects were instructed to land in a controlled manner on both feet. A further attempt was allowed if the subject fell or touched the floor with any body part other than the feet. The length of the jump was measured from the rear edge of the piece of tape to the rear edge of the impact area, rounded to the nearest centimeter. A sports field measuring tape was used for the measurements. The measuring tape was 10 meters long, with both meters and centimeters as measurement points. The longest jump of two was registered.
2.4 Statistical analyzes
To calculate if data (BH, VJ, SLJ) was normally distributed a Shapiro-Wilks test of normality was performed. The test showed that no significant (p < 0.05) departure from normality was found for the total sample nor when stratified for groups of men and women. Parametric sta- tistics were therefor used. Mean and standard deviation (SD) were used to describe results. An Independent Samples T-Test was used to compare differences between groups of men and women. Bivariate Pearson correlation was used to determine the strength of, and if there were significant relationships between the variables studied (Table 2). The significance level was set at p < 0.05 for all tests. Furthermore, in order to estimate how much of the variations in the jump length could be explained by the body height, the correlation coefficient (r) was squared, whereupon the Coefficient of determination (R2) was obtained. The statistics pro- gram SPSS version 27 (IBM Corp., New York, USA), was used to analyze the data. Tables and charts were created in Numbers version 11.0 (Apple Inc., Cupertino, USA)
Table 2. Levels for defining the strength of the correlations.
Digit interval Correlation levels
0.00-0.20 Very low
0.20-0.40 Low
0.40-0.70 Moderate
0.70-0.90 High
0.90-1.00 Very high
Table shows correlation levels, first proposed by Guilford (cited in Conelly, 2012).
2.5 Ethical considerations
The study followed the ethical principles stated in the Declaration of Helsinki (The World Medical Association, 2021). Through an informed consent (Appendix 1), the prospective sub- jects were informed about the conditions for participation. Participation was voluntary, and the subjects could cancel their participation at any time. All personal data was treated confi- dentially. Personal data was replaced with a code which was stored separately from data and processed so that unauthorized persons could not access it. The results are reported at group level, however, all subjects were able to get access to their individual data upon request. Fur-
training within 48 hours of the test session (Appendix 1). Testing procedures and informed consent were permitted by Halmstad University.
2.6 Social considerations
This study may be helpful for those who want to achieve better results on SLJ, to increase the understanding of which factors contribute to the result and thus create more effective training programs. This study is particularly important for the individual woman seeking employment as a firefighter, by reviewing the tests to inquire women in general do not end up at a disad- vantage compared to men. This due to a variable that the test itself does not intend to meas- ure. Women should not be excluded from the profession on unreasonable grounds (SFS 2008:567). The risk with possible unequal tests is an overly homogeneous workforce, which will affect the ability to provide equal service to the citizens (MSB, 2018). Hopefully this study, in one way or another, can contribute to the work to achieve equality between women and men as colleagues in the firefighter profession. Furthermore, the study is important from a global perspective, since the United Nations (n.d.) Sustainable Development Goal 5 addresses gender equality, and this study is a small but important contribution to that goal.
3. Results
Fourteen (n = 14) firefighter trainees met the inclusion criteria and participated in the study.
Subjects' age, body mass index (BMI) and number of workouts per week were 29 ± 7 years old, 25 ± 2 kg/m2 and 4 ± 1 workouts (at least 30 minutes) per week. When stratified for groups of men (n = 9) and women (n = 5), there were no significant differences (p < 0.05) be- tween the groups (Table 3). Descriptive statistics of the results from the three different meas- urements (BH, VJ and SLJ) is presented in Table 4.
Table 3. Descriptive statics of subjects included in the study.
Subjects (numbers) Age (years) BMI (kg/m2) Workouts (number / week)
All subjects (n = 14) 29 ± 7 25 ± 2 4 ± 1
Men (n = 9) 28 ± 7 25 ± 3 4 ± 1
Women (n = 5) 30 ± 8 24 ± 1 5 ± 1
Results are reported in mean ± Standard deviation.
Table 4. Results from measurements of body height (BH), vertical jump (VJ) and standing long jump (SLJ).
Variables All subjects
(n = 14) Men
(n = 9) Women
(n = 5) Mean difference
P-value
BH (cm) 177.2 ± 8.7 181.1 ± 8.1 170.3 ± 4.7 10.8 0.019 VJ (cm) 48.9 ± 9.9 55.2 ± 5.4 37.4 ± 1.9 17.8 < 0.001 SLJ (cm) 210.7 ± 31.2 229.9 ± 19.9 176.2 ± 7.5 53.7 < 0.001 Results are reported in centimeters (cm) and presented in mean and ! Standard deviation.
3.1 Correlation between body height and jump length
Results indicated a positive linear relationship between BH and SLJ. This meaning, those who are taller jumps longer compared to those that are shorter. Further analyzes showed a moder- ate correlation (r = 0.572, p = 0.033) between BH and SLJ. The coefficient of determination (R2) indicated that 33 % of the jump result can be attributed to variations in BH, while the re- maining percentage depends on other factors (Figure 1, Table 5). These results changed sub- stantially when the analyzes were performed separately for men and women, to a very low correlation level (r = 0.106 respective r = 0.166) between BH and SLJ, and no significant (p >
0.05) results (Figure 2, Table 5).
Table 5. Correlation between body height (BH) and jump length (SLJ).
Subjects r P-value
All subjects 0.572 0.033
Men 0.106 0.786
Women 0.166 0.790
Table shows correlation coefficients (r) and respective p-value for the correlations be- tween body height (BH) and jump length (SLJ). The results are presented for all sub- jects (n = 14) compiled and stratified for groups of men (n = 9) and women (n = 5).
3.2 Correlation between jump height and jump length
Results indicated a positive linear relationship between VJ and SLJ. This meaning, those who perform well at the VJ also perform better at the SLJ, compared to those who perform worse.
Further analyzes showed a strong correlation (r = 0.862, p < 0.001) and the coefficient of de- termination (R2) indicated that 74 % of the jump result in VJ could be explained by factors in- volved in SLJ, and vice versa (Figure 3, Table 6). These results changed substantially when the correlation analyze, between VJ and SLJ, was performed separately for men and women.
We then found a moderate correlation level for men and low for women (r = 0.414 respective r = 0.387) between VJ and SLJ (p > 0.05) (Figure 4, Table 6).
Table 6. Correlation between jump height and jump length.
Subjects r P-value
All subjects 0.862 < 0.001
Men 0.414 0.268
Women 0.387 0.520
Table shows correlation coefficients (r) and respective p-value for the correlations be- tween jump height (VJ) and jump length (SLJ). The results are presented for all sub- jects (n = 14) compiled and stratified for groups of men (n = 9) and women (n = 5).
4. Discussion
The present study examined the strength of the relationship between BH and SLJ, as well as SLJ and VJ, for firefighter trainees. The main results of the current study show a significant moderate correlation between BH and SLJ (r = 0.572). Between the variables VJ and SLJ we found a significant strong correlation (r = 0.862). However, the results changed substantially when the analyzes were performed separately for men and women, with a very low correla- tion between BH and SLJ (r = 0.106 respective r = 0.166). Between VJ and SLJ there were then a moderate correlation for men and low for women (r = 0.414 respective r = 0.387).
4.1 Result discussion
4.1.1 Correlation between body height and jump length
In this study a moderate correlation was shown between BH and SLJ. These results are in line with previous studies on children and adolescents, showing BMI affects the jump length at SLJ (r= 0.666) (Castro-Pinero et al., 2009; Milliken et al., 2008). It is reasonable that the cor-
the analysis. Furthermore, our results substantially changed when the analyzes were per- formed separately for men and women, the strength of the correlation weakened. The previ- ous study by Wu et al. (2003), studying young women only, also found a low correlation level between jump length and BH (r = 0.18 - 0.29). It seems from this that BH can to some extent affect the result in SLJ, but BH is not a decisive factor for the jump result. This study suggests 1 - 33 % of the jump result can be attributed to variations in BH while the remaining percent- age depends on other factors. Likewise, BH shown not to be a decisive factor for who com- pleted and did not complete the work-related course (Candidate Physical Ability Test) with stages relevant to the firefighter profession in the USA (Williams-Bell et al., 2009). Further studies should therefore continue to evaluate the recruitment tests for firefighters to find a suitable field test that, as far as possible, excludes the effect of BH. This in order to increase the conditions for gender equality in the firefighter profession.
4.1.2 Correlation between jump height and jump length
In this study a strong correlation was shown between VJ and SLJ. These results are in line with previous studies showing a moderate to strong correlation between VJ and SLJ (r = 0.61 - 0.911) (Castro-Pinero et al., 2010; Markovic et al., 2004). Our results suggest that 74 % of the variance in VJ is correlated with the variance in SLJ, while the remaining percentage de- pends on other factors. We cannot fully explain the remaining 26 %, but we can at least com- ment on the most obvious biomechanical similarities and the differences between the two tests. Both tests use a natural arm swing together with a countermovement, but the jumping directions differentiates the tests. In VJ, the body moves upwards. In SLJ, the body moves up and forward. Thereby, motor unit recruitment (neural control) will look a bit different be- tween the two jumps due to which and how many motor units are involved in the movements (Baechle et al., 2008, p. 75 - 76). Neural control being mentioned as the most important factor for maximum muscular power (Ratamess et al., 2009). How this would affect the validity of the various jump tests, for the target group firefighter trainees, must be further investigated.
Firefighters’ rescue, pulling and stairs work, are tasks depended on maximum muscular power (Lindberg et al., 2015). These tasks mean movements in both directions, both upward and for- ward. Overall, our findings suggest that VJ could possibly be an alternative field test for SLJ, to assess leg power when recruiting new firefighters. However, further studies are needed to investigate the correlation between VJ and the firefighter's rescue, pulling and stairs work.
4.1.3 Differences between men and women
In our study there was no significant difference between the group of men compared to the group of women regarding age, BMI or number of workouts per week. However, there was a significant difference between the group of men and the group of women, in all three meas- urements (BH, VJ and SLJ). These differences between the sexes are in line with previous jump studies (Castro-Pinero et al., 2009; Lindberg et al., 2011; Nahdiya & Mohd, 2012). In the study by Nahdiya et al. (2012) men jumped 26 % higher (p < 0.001) compared to women.
In the study by Lindberg et al. (2011) men jumped longer than women, but the woman who jumped the longest had better results than the man who jumped the shortest (p < 0.05). In terms of absolute strength, i.e. how much one can lift at most once (1 RM), men are generally stronger compared to women (Bishop et al., 1987; Lindberg et al., 2011). However, Bishop et al. (1987) showed that groups of men and women with similar long-term participation in sports activities and by measuring the relative strength, the differences between the sexes were reduced. The present study did not measure the actual leg power, and we cannot fully explain the differences between the sexes. Hopefully, however, the study can be helpful for those who want to achieve better results at SLJ, to increase the understanding of which factors contribute to the result and thereby create more effective training programs.
4.2 Method discussion
The strength of this study is related to the aim. Equality between men and women is an im- portant issue (United Nations, n.d.). This study addresses that issue by further evaluate fire- fighter's recruitment tests, based on new findings, and by taking biological sex differences such as BH into account. No previous study to our knowledge has, for firefighter trainees, ex- amined the strength of the correlation between BH and SLJ, nor between VJ and SLJ.
Thereby, our study complements earlier work (Castro-Pinero et al., 2009; Lindberg et al., 2015; Milliken et al., 2008; Nahdiya et al., 2012). The main limitations in this study are re- lated to its design. The study is small to the number of subjects (n = 14), and thereby we can- not rule out the risk of random error (Dohoo, 2013). We must also consider the risk of sys- tematic error generated by unmeasured confounders. Other important correlates of jump length exist but were not measured in the present study, i.e. actual leg power, body weight, arm motion and initial knee angle (Castro-Pinero et al., 2009; Lindberg et al., 2015; Milliken
recommend increasing the sample size and include more confounding factors. Furthermore, most subjects in this study were familiar with SLJ, VJ on the other hand was somewhat unfa- miliar. Both tests considered technical (Castro-Pinero et al., 2010). To reduce the risk of test results improving due to a learning effect, future studies should further examine both jump tests, with subjects more familiar with the tests (Manske et al., 2013). One can also discuss the effect of two different types of floor surfaces when carrying out the jump tests. In future studies we recommend floor surfaces to be the same for all test sessions (Beachle et al., 2008, p. 253).
4.2.1 Differences between men and women
Men and women differed significantly in all three measurements. When the correlation ana- lyzes were performed separately, the strength of the correlations weakened. This means that there is a risk of making correlation calculations on the compiled results since it could give an apparent and incorrectly high correlation coefficient (Eljertsson, 2012, p. 230 - 231). We jus- tify the analysis on the compiled results, with the low number of subjects, in order to maintain analytical power. In addition, target population consists of both men and women. During a re- cruitment, men and women undergo the same tests, with the same reference values (Table 1), and are compared against each other. Thereby we argue they should be seen as a group. How- ever, more studies with additional confounders are needed to find out what this difference is due to, and if it remains when more subjects are included in the study. Future studies, how- ever, need to take this discovery into account and include both men and women in order to obtain the most valid and equal tests for this target population.
5. Conclusion
The result from this study is in line with aforementioned work and supports the hypothesis that BH to some extent can affect the jump result at SLJ. Our study complements earlier work and indicates that these results are also applicable to firefighter trainees. The findings in this study indicates VJ could possibly be an alternative field test for SLJ, to assess leg power when recruiting new firefighters. Additional studies are required to investigate the correlation between SLJ and VJ with additional confounders, such as actual leg power, and also the cor- relation between VJ and firefighters heaviest among most common work tasks.
References
Ashby, B. M. & Heegaard, J. H. (2002). Role of arm motion in the standing long jump. Jour- nal of Biomechanics, 35(12), 1631-1637. doi: 10.1016/S0021-9290(02)00239-7
Baechle, T. & Earle, R. (2008). Essentials of strength training and conditioning.
Champaign: Human Kinetics Publishers.
Bos, J., Mol, E., Visser, B. & Frings-Dresen, M. H. W. (2004). The physical demands upon (Dutch) fire-fighters in relation to the maximum acceptable energetic workload. Ergonomics, 47(4), 446-460. Doi: 10.1080/00140130310001643283
Castro-Pinero, J., Gonzalez-Montesinos, J. L., Mora, J., Keating, X. D., Girela-Rejon, M. J., Sjöström, M. & Ruiz, J. (2009). Percentile values for muscular strength field tests in children aged 6 to 17 years: influence go weight status. National Strength and Conditioning Associa- tion, 23(8), 2295–2310.
Castro-Pinero, J., Ortega, F. B., Artero, E. G., Girela-Rejon, M. J., Mora, J., Sjöström, M. &
Ruiz, J. R. (2010). Assesing muscular strength in youth: usefulness of standing long jump as a general index of muscular fitness. Journal of Strength and Conditioning Research, 24(7), 1810–1817.
Chamari, K. & Padulo, J. (2015). ”Aerobic” and “Anaerobic” terms used in exercise physiol- ogy: a critical terminology reflection. Sports Medicine, 1(9). doi: 10.1186/s40798-015-0012-1
Conelly, L. (2014). Correlation. Medsurg nursing: official journal of the Academy of Medical- Surgical Nurses, 21(3), 171-172.
Dohoo, I. R. (2014). Bias - Is it a problem, and what should we do?. Preventive Veterinary Medicine, 113, 331-337.
Ejlertsson, G. (2012). Statistik för hälsovetenskaperna. Lund: Studentlitteratur AB.
Etikprövningsmyndigheten. (2021). Stödmall Forskningspersonsinformation med GDPR.
Downloaded 2021-01-17 from https://etikprovningsmyndigheten.se/for-forskningsperson/
Gavhed, D., Brodin, L., Johansson, E., Bohlund, L., Thoresson, T., Åslund, C. & Lundström S. (2001). Brandmannens fysiska förmåga: Delrapport 1 – Typinsatser. Karlstad: Räddnings- verket.
Hilmersson, E. (2020, December 21st). Räddningstjänstens fystester döms ut som förlegade och orättvisa. Göteborgs-Posten. Viewed 2021-06-04, < https://www.gp.se/nyheter/göte- borg/räddningstjänstens-fystester-döms-ut-som-förlegade-och-orättvisa-1.38359142>
Ivansson, G. (2012, May 25th). Fysiska krav för brandmän klara. Tjugofyra7. Viewed 2021- 06-04, <https://www.tjugofyra7.se/arkivet/Avdelningar/Nyheter/Fysiska-krav-klara/>
Lindberg, A. & Malm, C. (2011). Brandmannens fysiska förmåga: Delrapport 3- Fysiska gränsvärden. Karlstad: Myndigheten för samhällsskydd och beredskap.
Lindberg A-S., Oksa J., Antti H. & Malm C. (2015). Multivariate Statistical Assessment of Predictors of Firefighters’ Muscular and Aerobic Work Capacity. PLoS ONE, 10(3).
McArdle, W. D., Katch, F. I. & Katch, V. L. (2010). Exercise Physiology. Philadelphia: Lip- pincott Williams & Wilkins
Markovic, G., Dizdar, D., Jukic, I. & Cardinale, M. (2004). Reliability and factorial validity of squat and countermovement jump tests. Journal of Strength and Conditioning Research, 18(3), 551–555.
Malm, C., Lindberg, A. & Stene, F. (2005). Brandmannens fysiska förmåga: Delrapport 2 - Fysiologiska tester. Karlstad: Räddningsverket.
Manske, R. & Reiman, M. (2013). Functional performance testing for power and return to sports. Sports Health, 5(3), 244-250.
Pagaduan, J. C., Pojskić, H., Užičanin, E. & Babajić, F. (2012). Effect of Various Warm-Up Protocols on Jump Performance in College Football Players. Journal of Human Kinetics, 35, 127-132. doi:10.2478/v10078-012-0086-5
Peterson, M. D., Dodd, D. J., Alvar, B. A., Rhea, M. R., & Favre, M. (2008). Undulation training for development of hierarchical fitness and improved firefighter job performance.
Journal of Strength and Conditioning Research, 22(5), 1683–1695.
Ratamess, N. A., Alvar, B. A., Evetoch, T. K., House, T. J., Kibler, W. B., Kraemer, W. J. &
Triplett, N. T. (2009). Progression models in resistance training for healthy adults. Medicine
& science in sports & exercise, 41(3), 687-708. doi:10.1249/MSS.0b013e3181915670
SFS 2008:567. Diskrimineringslag. Stockholm: Arbetsmarknadsdepartementet.
Statistics Sweden. (2017). Varannan svensk har övervikt eller fetma. Viewed 2021-02-22,
<https://www.scb.se/hitta-statistik/artiklar/2018/varannan-svensk-har-overvikt-eller-fetma/>
The Swedish Civil Contingencies Agency. (2018). En räddningstjänst för alla:
Handbok i jämställdhet för räddningstjänsten. Karlstad: MSB.
The World Medical Association. (2021). WMA decleration of Helsinki – Ethical principles for medical research involving human subjects. Viewed 2021-01-24, <https://www.wma.net/poli- cies-post/wma-declaration-of-helsinki-ethical-principles-for-medical-research-involving-hu- man-subjects/>
Thomas, J. R., Nelson, J. K. & Silverman, S. J. (2011). Research methods in physical activity.
Champaign: Human Kinetics.
Tsurubami, R., Oba, K., Samukawa, M., Takizawa, K., Chiba, I., Yamanaka, M. & Tohyama H. (2020). Warm-Up Intensity and Time Course Effects on Jump Performance. Journal of Sports Science and Medicine, 19, 714-720.
United Nations. (n.d.). Sustainable Development Goals. Viewed 2021-05-14,
Williams-Bell, F. M., Villar, R., Sharratt, M. T. & Hughson, R. L. (2008). Physiological De- mands of the firefighter candidate physical ability test. Medicine & science in sports & exer- cise, 41(3), 653-662. doi: 10.1249/MSS.0b013e31818ad117
Wu, W., Wu, J., Lin, H. & Wang, G. (2003). Biomechanical analysis of the standing long jump. Biomedical engineering applications, basis & communications, 15, 186-192.
Appendices
Appendix 1
Informed consent
Informativt samtyckeVi vill fråga dig om du vill delta i en studie. Studien är ett examensarbete i Biomedicin inrikt- ning träningsfysiologi, på grund-/kandidatnivå, som ges av Högskolan i Halmstad. Studien genomförs i samverkan med Räddningstjänsten Halmstad som en del i arbetet att bli en jäm- ställd förvaltning, vilket är ett av målen i räddningsnämndens verksamhetsplan 2021-2023. I det här dokumentet får du information om studien och om vad det innebär att delta.
Vad är det för projekt och varför vill ni att jag ska delta?
Inom räddningstjänsten behövs en varierad bakgrund för att kunna leverera en jämställd ser- vice till invånarna. I dagsläget råder en skev könsfördelning inom kommunal räddningstjänst, med endast ett par procent av brandmännen som är kvinnor. Många kvinnor har svårt att klara de fysiska gränsvärdena på anställningstesterna. I denna studie ämnar vi undersöka sambandet mellan hoppförmåga i olika riktningar och kroppslängd. Du tillfrågas att delta i studien ef- tersom du studerar till brandman. Din medverkan i studien är viktig för räddningstjänstens ar- bete med att bli en jämställd förvaltning.
Hur går studien till?
Att delta innebär att du vid ett testtillfälle genomför tre olika tester: mätning av kroppslängd, stående längdhopp, och vertikalt hopp. Testförfarandet inleds med en standardiserad upp- värmning. Den består av jogging och dynamisk stretching i cirka 10-15 minuter.
Vid testtillfället ska du vara skadefri och frisk. Vi uppmanar till vila från träning dagen före testtillfället, samt att undvika tung träning två dagar innan. Vi rekommenderar att inte äta nå- gon stor måltid mindre än två timmar före testerna. Vid testperioden ska du ha på dig trä- ningskläder och -skor.
Testerna kommer att genomföras under mars-april månad på Räddningstjänsten i Halmstad, alternativt på Räddningsskolan Revinge. Räkna med att testtillfället tar cirka 45 minuter. Du som samtycker till att delta i studien går in via följande länk:
https://forms.gle/mQ9u9gX3t97qA85F6 för att svara på lite frågor om dina träningsvanor samt boka en tid för testtillfället. Med anledning av Covid-19-pandemin bokar och genomför vi testtillfällena enskilt. Formuläret tar ca 5 minuter att fylla i.
Möjliga följder och risker med att delta i studien
Förhoppningsvis kan studien bidra till att öka jämställdheten inom räddningstjänsten genom
Alla som deltar får möjligheten att komma och provträna på arbetsbanan som Räddningstjäns- ten Halmstad använder sig av vid nyrekrytering. Du kan få tips som kan vara bra att ha om du vill söka anställning i Halmstad framöver.
Testerna i denna studie inbegriper explosiva hopp som skulle kunna leda till skada i form av muskelbristning. Vi minskar risken genom den obligatoriska uppvärmning, och överenskom- melsen att inte genomföra någon tyngre form av träning inom 48 timmar innan testtillfället.
Med anledning av pågående Covid-19-pandemi kommer extra försiktighetsåtgärder att vidtas under testsessionerna: en deltagare i taget, håll avstånd från varandra samt att utrustningen de- sinficeras både före och efter varje deltagare. Vi uppmanar att inte använda kollektivtrafik till testsessionerna och att du avstår från att komma om du har symtom.
Vad händer med mina uppgifter?
Resultaten kommer redovisas på gruppnivå och ingen kommer veta vem som fått vilket resul- tat. Samtliga personuppgifter behandlas konfidentiellt. Personuppgifter ersätts med kod vilken förvaras separat från insamlad data, och behandlas så att inte obehöriga kan ta del av dem. Ef- ter studien kommer data förvaras inlåst på Högskolan i Halmstad under 10 år. Ansvarig för dina personuppgifter är Högskolan Halmstad. Enligt EU:s dataskyddsförordning har du rätt att kostnadsfritt få ta del av de uppgifter om dig som hanteras i studien, och vid behov få eventu- ella fel rättade. Du kan också begära att uppgifter om dig raderas samt att behandlingen av dina personuppgifter begränsas. Om du vill ta del av uppgifterna ska du kontakta projektan- svarig.
Hur får jag information om resultatet av studien?
Studieresultatet kommer att sammanfattas i en rapport. Möjligheten att ta del av studiens re- sultat kommer finnas då den publiceras i databasen DiVA vid godkänd examination.
Individuella resultat delges vid respektive testtillfälle, om du så önskar.
Deltagandet är frivilligt
Ditt deltagande är frivilligt och du kan när som helst välja att avbryta deltagandet. Om du väl- jer att inte delta eller vill avbryta ditt deltagande behöver du inte uppge varför. Om du vill av- bryta ditt deltagande ska du kontakta projektansvarig. Ingen ersättning utgår för ditt delta- gande. Under testerna är du försäkrad genom en personskadeförsäkring via Högskolan.
Ansvariga för studien"
Projektansvarig
Mimmi Bringsén-Bornegrim 072-3273797
mimbri21@student.hh.se
Handledare Emma Haglund
Emma.Haglund@hh.se
Samtycke till att delta i studien
! Jag har fått information om studien och har haft möjlighet att ställa frågor. Jag får behålla den skriftliga informationen.
! Jag samtycker till att delta i studien Hoppförmåga och kroppslängd: en sambandsstudie på brandmannastudenter.
! Jag intygar att jag förstår varför jag är med i studien samt vilka krav som ställs på mig som testdeltagare.
! Jag intygar att jag vet om att jag när som helst kan välja att inte längre delta i studien, utan att behöva nämna någon orsak.
! Jag samtycker till att uppgifter om mig behandlas på det sätt som beskrivs i deltagarinform- ationen.
Deltagare
Plats och datum Underskrift
Appendix 2
Questionnaire
Appendix 3
Warm-up protocol
Uppvärmningsprotokoll
Vad? Hur?
1. Jogging 5 minuter i måttlig till hög intensitet
2. Benpendling Repetitioner: 5-10 st per ben
Utförande: stå på ett ben, med eller utan stöd, och pendla det andra benet framåt och bakåt i en kontrollerad rörelse. Gradvis ökning av rörel- seomfång och hastighet.
Uppvärmningsprotokoll
3. Rumpspark Repetitioner: 5-10 per ben
Utförande: sparka hälarna mot rumpan, växelvis, i en kontrollerad rörelse. Gradvis ökning av rörel- seomfång och hastighet.
Uppvärmningsprotokoll
4. Växelvis översteg Repetitioner: 5-10 steg åt varje håll
Utförande: förflyttning i sidled genom växelvis översteg (framför/bakom) i en kontrollerad rö- relse. Jobba även med armarna för att skapa en rotation i bålen. Måttlig till hög intensitet.
Uppvärmningsprotokoll
5. Höga knän Repetitioner: 5-10 per ben
Utförande: stå med fötterna höftbrett isär, dra sedan upp knäna växelvis mot magen i en kon- trollerad rörelse. Håll överkroppen upprätt, och jobba på tårna. Gradvis ökning av rörelseomfång och hastighet.
Uppvärmningsprotokoll
6. Utfallssteg med vridning Repetitioner: 5-10 per sida
Utförande: gör ett kontrollerat utfallssteg med vänster ben, och stanna med knäet 3-5 cm ovan golvet. Sträck höger arm upp mot taket. Böj se- dan bålen kontrollerat över det vänstra benet, och känn att det sträcker i sidan. Återgå till ut- gångsposition. Gör sedan samma sak med hö- ger ben fram, och vänster arm upp och åt sidan.
Uppvärmningsprotokoll
7. Sidohopp Repetitioner: 5-10 per sida
Utförande: förflyttning i sidled genom sidohopp med armrörelser. Måttlig till hög intensitet.
Uppvärmningsprotokoll
8. Knäböjshopp med rotation Repetitioner: 5-10 per sida
Utförande: stå med fötterna axelbrett isär, ta ett steg 45 grader bakåt och böj knäna. Detta är ut- gångspositionen. Hoppa och växla fötternas po- sition (fram/bak). Ta hjälp av armarna i rotat- ionen. När höger ben är fram ska vänster arm vara fram, och vice versa. Rörelsen ska vara kontrollerad, med gradvis ökning av rörelseom- fång och hastighet.
Uppvärmningsprotokoll
9. Träningshopp: vertikalt hopp Repetitioner: 3-5 st
Utförande: stå med den dominanta sidan närm- ast väggen. Hoppa så högt du kan genom att ta fart med ben och armar. I hoppet sträcker du den dominanta armen och markerar så högt upp du kan på väggen.
Uppvärmningsprotokoll
10. Träningshopp: stående längdhopp Repetitioner: 3-5 st
Utförande: stå med fötterna höftbrett isär, och tårna bakom markerad linje. Från stillastående utför du sedan ett jämfotahopp, så långt du kan.
Armrörelser är tillåtna. För att hoppet ska god- kännas måste du landa kontrollerat på bägge fötterna, utan att röra golvet med någon annan kroppsdel.
Besöksadress: Kristian IV:s väg 3 Postadress: Box 823, 301 18 Halmstad Telefon: 035-16 71 00
Mimmi Bringsén-Bornegrim
